1. Field of the Invention
The present invention relates to an optical device to be installed in an optical network unit in optical multiplex communication by optical signal carriers of different wavelength components multiplexed together, and also to a manufacturing method therefor, and more particularly to an optical device for an optical network unit, which incorporates as optical elements computer generated holograms utilizing optical diffraction, and yet to a manufacturing method therefor.
2. Related Art
In recent years, the so-called `Fiber to the Home` project is being pushed forward by which to extend optical fibers to respective homes to enable optical communications with a large traffic capacity.
According to this project, a multiplexed light having component beams of wavelength bands of 1.3 .mu.m and 1.55 .mu.m, for example, are transmitted to the optical network units in the respective homes.
In the optical network units, there is provided an optical device, including a wavelength demultiplexer for separating a multiplexed light into beams of respective wavelengths, and an optical coupler for separating an optical path for one wavelength to enable bi-directional communication by one wavelength.
By this optical device, a multiplexed light is separated into wavelength components of different wavelength bands to be transmitted to various pieces of terminal equipment.